Vacuum cleaner motor-fan combination units for use to pick up water or moisture burdened air are of the by-pass type wherein the working air drawn into the fan section of the unit is exhausted through a peripheral discharge which in larger units usually is in the form of a tangential scroll. Even though the moisture burdened working air flow is directed away from the bearing area of the motor, when such by-pass vacuum cleaners are used as water extraction cleaners for cleaning rugs, the vacuum cleaners are susceptible to premature bearing failure because a strong vortex action in the bearing area tends to draw some moisture or foam to the bearing. In such cleaning applications the moisture or foam usually contains a detergent that tends to wash the bearing lubricant out of the bearing and produce premature bearing failure.
In order to overcome the problem of premature bearing failure, prior art devices have introduced a flow of air from a separate air inlet at or near the periphery of the motor-fan housing through a flow path passing in the vicinity of the motor bearing and discharging into the working air flow path near the working air outlet. This flow of air is usually produced by an auxiliary fan located on, and driven by, the motor-fan shaft with the eye of the fan in the vicinity of the motor bearing. Other prior art has proposed that the entire flow of cooling air for the motor flow past the motor bearing and be discharged, with the working air, through a series of openings about the periphery of the fan section housing.
While the prior art arrangements have been effective in reducing premature bearing failure the use of peripheral air inlets has required that separate baffles must be used to separate the various air flow paths and the use of the full cooling air flow is not compatable with a reverse air flow check valve which provides protection in the event that the vacuum cleaner is tipped over or the working air outlet is blocked to prevent the normal outflow or working air. In the present invention a part of the conventional cooling air flowing past the motor flows through a small passageway in the central area of the motor housing to provide the sealing air to sweep any detergent carrying moisture or foam away from the bearing area and into the working air flow path near the working air outlet. The use of a part of the motor cooling air flow to provide the sealing air not only results in a more economical design and lower manufacturing costs, but also the cooling air fan assists the sealing air fan to provide the flow of sealing air.